Article handling equipment

ABSTRACT

A suction depanner is provided having an automatic height adjustment means responsive to the height of the product to be depanned. Further, the depanner is provided with self-centering guides for aligning the product.

United States Patent Maude I 1451 Oct. 24, 1972 [54] ARTICLE HANDLINGEQUIPMENT [72] Inventor: Stanley Morgan Maude, llkley, En-

gland [73] Assignee: Alto Corporation, York, Pa.

[22] Filed: Sept. 4, 1970 [2]] Appl. N0.: 69,786

[52] US. Cl ..214/309 51 Int. Cl. ..A2lb 3/18 [58] Field of Search..2l4/309 [56] References Cited UNITED STATES PATENTS 3,l70,58l 2/1965Temple ..214/309 2,742,137 4/1956 Carroll ..l98/33.1 3,570,693 3/1971Peyton ..2l4/309 Primary Examiner-Gerald M. Forlenza AssistantExaminer-George F. Abraham Artorney-Thomas Hooker [5 7] ABSTRACT Asuction depanner is provided havingan automatic height adjustment meansresponsive to the height of the product to be depanned. Further, thedepanner is provided with self-centering guides for aligning theproduct.

14 Claims, 9 Drawing Figures P'ATENTEDum 24 m2 SHEET 1 0F 8 R O T m. V m

STANLEY MORGAN MAUDE PATENTEDncI 24 m2 SHEET 2 0F 8 INVENTOR STANLEYMORGAN MAUDE N f'fTORNEYS KO l-N PATENTEDHBI 24 I972 3.700. 1- 2 9 sum 30F 8 INVENTOR STANLEY MORGAN MAUDE PATENTED um 24 m2 SHEET t UP 8INVENTOR @XNLEY MORGAN MAUDE MZTTORNEYS PATENTED 24 2 3.700. 129

sum 5 0F 8 FIG 5 m s\ m INVENTOR STANLEY MORGAN MAUDE ATTORNEYS IPATENTEDHBI 24 I972 SHEET 8 BF 8 INVENTOR 1 LIFIFF LI STANLEY MORGANMAUDE ATTORNEYS PATENTEDUCI24 1 I 3.700.129

FIG. 7

INVENTOR STANLEY MORGAN MAUDE J 5 BY (\1 N ATTORNEYS PATENTEDOcI24 I9123.700.129

saw 8 0F 8 STANLEY MORGAN MAUDE E B W F ATTORNEY 5 ARTICLE HANDLINGEQUIPMENT This invention relates to so-called suction depanners for usein bakeries for depanning bread, buns and the like food products.

A suction depanner of the kind to which the invention relates isdescribed in U.S. Pat. No. 3,325,025. The pans or panstraps containingthe items to be depanned are fed along a pan conveyor beneath a pickupconveyor which is adapted to individually grip the items by suction andlift them from the pans.

In the depanner described in U.S. Pat. No. 3,325,025 the pickup conveyorcan be raised or lowered manually to set the height of the pickupconveyor above the pan conveyor to suit the height of the loaves orother items to be depanned. Also lateral guides (not described in theabove-mentioned U.S. specification) are arranged at opposite sides ofthe pan conveyor for centering the pans beneath the suction conveyor.These guides are manually adjustable-t suit the width of the pans. Thuswhen changing a bakery line over from one size article to another it isnecessary to shut down the line for a short while to enable the pickupconveyor and the lateral guides to be adjusted. If these adjustments areforgotten, as may well happen, there is' grave danger of the depanneritself being damaged, quite apart from the loss of production andpossible damage to the pans.

One feature of the present invention is to provide a suctiondepannerwith'automatic height adjustment of the pickup conveyor. Thiscan be achieved by providing a sensor in advance of the pickup conveyoradapted to sense the height of the items in the pans as they approachthe pickup conveyor. The sensor can comprise a feeler adapted to operatea hydraulic or pneumatic control valve or electrical contacts or anelectrical resistor. Alternatively the sensor can comprise a verticalrow of fixed photoelectric devices or two photoelectric devices arrangedon the pickup conveyor one above the other. A hydraulic or pneumaticjack or an electrically driven screw jackcan be provided for raising andlowering the pickup conveyor responsively to signals received from thesensor.

Another feature of the invention is to provide selfcentering guides forthe pans on the pan conveyor. These can comprise a pair of pivoted guideanns arranged at opposite sides of the pan conveyor and adapted to swinginwardly towards one another, preferably under spring bias. As the pansare advanced by the pan conveyor they come into engagement with theguide arms and are thereby centered beneath the pickup conveyor. Thearms are preferably coupled together mechanically so that they can onlyswing simultaneously but in opposite directions. The coupling means maycomprise a connecting rod linking two cranks provided respectively onthe guide arms but out of phase with one another by substantially 180.Alternatively a twisted belt drive or a gear train can be provided asthe coupling means. Advantageously in accordance with a feature of theinvention rollers are joumalled to the free ends of the guide arms.

The invention is further described, by way of example with reference tothe drawings, of which FIGS. 1 to diagrammatically illustrate variousparts of a suction depanner constructed generally as described in theabove-mentioned U.S. specification but provided with automatic heightadjustment in accordance with one embodiment and self-centering guideswhereby no adjustment of the depanner is required when changing from onesize loaf or other item to another size, and of which FIGS. 6 to 9accompany this Complete Specification and illustrate a second embodimentof automatic height adjustment. In the drawings:

FIG. 1 is a plan view of the self-centering guides,

FIG. 2 is a rear view of the self-centering guides,

FIG. 3 is a detail view of the downstream end of the pickup conveyor,

FIG. 4 is a detail of the support for the pickup conveyor,

FIG. 5 is a detail view of the upstream end of the pickup conveyor inaccordance with the first embodiment,

FIG. 6 is a side elevation of the second embodiment,

FIG. 7 is a plan view of the second embodiment,

FIG. 8 is a front elevation of the second embodiment, and

FIG. 9 is a block diagram of the control circuit of the secondembodiment.

The first embodiment of suction depanner, parts of which are shown inFIGS. 1 to S of the drawings, comprises an endless horizontal conveyorfor conveying the pans or panstraps containing loaves, buns or the likeitems to be depanned. A pickup conveyor is arranged above the panconveyor at a pickup station. The pickup conveyor comprises an endlessbelt whose lower run is a generally horizontal portion followed by agently rising portion. A suction chamber is arranged inside this beltand has an open face which is sealingly engaged by the horizontal andrising portions of the lower runfThe conveyor belt is perforated and hasattached thereto in registry with the perforations a multiplicity ofbellowslike suction cups made of soft rubber. As the belt passes beneaththe suction chamber, suction is applied through the perforations to thesuction cups. The height of the pickup conveyor above the pan conveyoris adjusted in the mannerhereinafter described so that the lower lips ofthe suction cups engage the tops of the loaves or other items to bedepanned. This enables a vacuum to be developed inside the suction cupswhich due to their bellows-like construction immediately tend tocontract to grip the loaves or other items and bodily lift them out ofthe pans. The rising portion of the lower run of the conveyor belt thenlifts the loaves clear of the pans. A discharge conveyor has an inletend extending beneath the rising portion of the conveyor band so thatwhen the suction cups pass beyond the end of the suction chamber thevacuum is released from the suction cups to deposit the loaves or otheritems on-the discharge conveyor.

All of the above features are more fully described in U.S. Pat. No.3,325,025 to which reference may be made as necessary to permit a morefull understanding of the present invention. Referring now specificallyto FIGS. 1 and 2 of the drawings, it is necessary that the pans 20 onthe pan conveyor 21 be accurately centered on the pan conveyor 21 as thepans pass beneath the pickup conveyor (not shown in FIGS. 1 and 2.) Suchcentering is achieved by a pair of guide arms 22 which are attached tovertical spindles 23 joumalled in fixed bearings 24. The guide arms 22are coupled together for simultaneous swinging movement in a horizontalplane by a connecting rod 25. The connecting rod 25 is pivoted to crankpins 26 and27 attached to discs 28' and 29 secured respectively to thelower ends of the spindles 23. The crank pins 26 and 27 are 180 out ofphase with one another so that the two guide arms 22 are constrained tomove simultaneously but in opposite directions, i.e. towards and awayfrom one another and from the longitudinal center line of the panconveyor 21. A tension spring 30 acts on the connecting rod 25 in adirection to urge the guide arms 22 towards one another. Rollers 31 arejoumalled to the free ends of the guide arms 22.

As the pans 20 are advanced by the pan conveyor 21 towards the pickupstation (which is to the right of that part of the depanner shown inFIG. 1) the pans come into engagement with the guide arms 22. Sincethese guide arms are constrained to move away from the longitudinalcenter line by equal amounts they act as a self-centering device toautomatically center the pans 20 on the pan conveyor. As the pansproceed between the guide arms the rollers 31 run along the side walls32 of the pans to hold the pans in a center position. While only one ortwo pans are shown in the drawings it will be appreciated that inpractice the pans follow one another continuously and generally inabutment with one another so that the rollers 31 are substantiallycontinuously running along the side walls 32 thereby holding the arms 22themselves out of substantial frictional engagement with the pans.

Referring now specifically to FIGS. 3, 4 and of the drawings there isshown therein the pickup conveyor 35 which comprises the endless belt 36having a plurality of bellows-like suction cups 37 attached thereto.While only one suction cup is shown it will be appreciated that thereare hundreds of suction cups attached to the conveyor belt 36. They arearranged in a large number of rows across the central portion of thebelt 36, there being about four suction cups in each row and the suctioncups in adjacent rows being staggered with respect to one another. Thebelt 36 has a large number of perforations such that each perforationcommunicates withthe interior of one of the suction cups 37. The lowerrun 38 of the belt 36 has a generally horizontal or slightly fallingportion 39 (FIG. 5) followed by a gently rising portion 40 (FIG. 3). Thebelt 36 is entrained about rollers 41 and 42 of which the roller 41 is adriving roller driven from an electric motor 43 by means of a belt drive44.

The rollers 41 and 42 are joumalled in a frame 45 on which the motor 43is mounted. The frame 45 is mounted for vertical movement in a stand 46the upperv cally guided by upper rollers 48 and lower rollers 49joumalled in the stand. Lower ends of the vertical box members 47 arejoined by a crosshead 50 which is pivoted to a piston rod 51 of ahydraulic jack 52 arranged beneath the pan conveyor. The crosshead 50 isshown in FIG. 4 in its lowered position and in its raised position asindicated at 50a. The cylinder of the hydraulic jack 52 is pivoted atits lower end to a bracket 53 at the base of the framework of thedepanner.

-FIGS. 3 and 5 also show the suction chamber 54 which is providedinternally with a number of internal longitudinal ribs which engage thebelt 36 to support the belt against the suction in the suction chamberand to define the generally horizontal portion 38 and the gently risingportion 40 of the lower run 38.

A pivot pin 55 of a feeler 56 is joumalled in the forward end of aprojecting arm 57 on the frame 45 of the pickup conveyor. The loaves orother items are advanced beneath the pickup conveyor in the direction ofthe arrow 58 and are engaged by the feeler 56 before they reach thesuction cups 37. The feeler 56 acts through a spring 59 on an operatingrod 60 which is connected to a servo-control valve 61 whose housing issecured to the frame 45. The servo-control valve 61 controls the flow ofhydraulic fluid to and from the hydraulic jack 52.

The depanner is provided with a small hydraulic pump which feeds ahydraulic reservoir (both not shown) to maintain a supply of hydraulicfluid for the jack 52. The supply and return lines are connected to theservo-control valve 61 which in turn is connected by two operating linesto the opposite ends of the jack 52. When the servo-control valve 61 isin its central position the hydraulic jack 52 is hydraulically locked inan adjusted position. Clockwise pivoting of the feeler 56 operates theservo-control valve to cause the jack 52 to raise and vice-versa. Thusas the loaves or other items to be depanned are engaged by the feeler 56the height of the pickup conveyor is rapidly and automatically adjustedby means of the servo-control valve 61 and the hydraulic jack 52 to suitthe height of the loaves or other items.

As the loaves or other items proceed beneath the slightly fallingportion 39 of the lower run 38 the lower lips 62 of the suction cups 37are pressed gently into engagement with the top of the loaf or otheritem and seal to the item. This allows the suction in the suctionchamber 54 to draw a vacuum in the suction cup 37 through thecorresponding perforation 63. The bellows-like suction cup immediatelycontracts and lifts the loaf out of the tin. The rising portion 40 ofthe lower run then lifts the loaf clear of the tin and when the end ofthe suction chamber 54 is reached the suction in the suction cup isbroken to deposit the loaf on a discharge conveyor (not shown).

In practice each item will generally be engaged by several suction cups37 but not all suction cups will be engaged by an item. This does leadto some loss of vacuum through the associated perforation but notsufficient to impair operation of the pickup conveyor. Since a ratherlarge suction fan is required this fan is mounted beneath the panconveyor and connected by flexible ducting (not shown) to the suctionchamber.

Thus it will be seen that the provision of self-centering guides for thebaking tins together with automatic height adjustment of the pickupconveyor provides a suction depanner which does not have to be manuallyadjusted despite variations and changes in the size of the loaves orother articles to be depanned.

The second embodiment of the suction depanner is shown in FIGS. 6, 7 and8 of the drawings. It comprises an endless horizontal conveyor which isentrained about end rollers 71 and 72 journalled in a fixed framework73. One of the rollers 71 and 72 is driven by means not shown. A pickupconveyor 74 is arranged above the pan conveyor 70 at a pickup station75. The pickup conveyor 74 comprises an endless perforated belt havingattached thereto a multiplicity of bellowslike suction cups made of asoft rubber as described more fully in the previously mentioned US. Pat.No. 3,325,025. A suction chamber 76 is arranged inside this belt and hasa lower open face which is sealingly engaged by the lowermost portion 77and a gently rising portion 78 of the lower run of the said perforatedbelt. A large suction fan 79 is arranged inside the framework 73 and itssuction inlet is connected by a flexible conduit 80 to aside extension81 of the suction chamber 76. The flexible conduit 80 can, for example,be of bellows-like construction. The outlet of the fan 70 dischargesthrough a filter 82. The fan 79 is driven by an electric motor 83.

It is necessary that the bread'pans or pan straps (not shown in FIGS. 6to 8) be accurately centered on the pan conveyor 70. Such centering iseffected by a pair of guide arms 84 which are shown in FIG. 7 butomitted from FIG. 6 for clarity. The guide arms are coupled together forsimultaneous swinging movement in a horizontal plane in oppositedirections. This can be achieved by a connecting, rod as describedpreviously with reference to FIGS. 1 and 2 of the drawings or by othersuitable means, such as a crossed belt drive or a gear train aspreviously mentioned. The guide arms 84 are spring biased towards oneanother like the guide arms 22 and can be provided at their free endswith rollers 85 like the rollers 31.

The endless perforated belt of the pickup conveyor 74 is entrained aboutrollers 86 and 87 of which the roller 87 is driven by a motor 88. Therollers 86 and 87 are journalled in a frame 89 which also supports themotor 88 andthe suction chamber 76. The frame 89 is mounted for verticalmovement in a stand 90 which straddles the framework 73 and effectivelyforms part thereof. This stand comprises uprights 91 and 92 arranged onopposite sides of the pan conveyor 70. Two vertical members 93 and 94effectively form part of the frame 89 and extend downwardly within theuprights 91 and 92 respectively. These vertical members 93 and 94 areconstrained to move vertically and are vertically guided by upperrollers 95 and lower rollers 96. The construction of the verticalmembers 93 and 94 and the uprights 91 and 92 may be substantially thesame as previously described with reference to FIGS. 3 and 4. The lowerends of the vertical member 93 and 94 are joined together by a crosshead97 which contains a nut of a screw jack 98. The spindle 99 of the screwjack is driven from an electric motor 100 through a suitable reductiongear 101.

A feeler 102 is attached to a spindle 103 which is journalled in avertically movable side support 104 and extends laterally of the panconveyor 70 so as to support the feeler 102 generally centrally abovethe pan conveyor. The spindle 103 is attached to the arm 105 (FIG. 9) ofa height measuring electrical transducer in the form of a potentiometer106. One end of a chain 107, passing around pulleys 108, 109 and 110which are journalled to the framework 73 is attached to the crosshead 97and its other end is attached to the vertically slidable column 141 ofthe side support 104 so that the support 104 is automatically raised andlowered when the pickup conveyor 74 is raised and lowered.

As shownin FIG. 9 the potentiometer 106 and a preadjustable referencepotentiometer 112 form two branches of a Wheatstone bridge circuit 113which is connected to a suitable electrical power source shown as abattery 114. The potentiometer arms 105and 111 are each connected to apositive error signalcomparator 115 and a negative signal comparator116. As more fully described hereinafter, the sensor 102 senses theheight of the loaves to be depanned with respect to the height of thepickup conveyor 74 and produces a corresponding signal at the slider arm105 of the potentiometer 106. If the pickup conveyor 74 is too low thecomparator 115 responds and produces a positive error signal which isamplified by an amplifier 117 to energize the solenoid 118 of a forwardcontactor 119. If the pickup conveyor 74 is too high the comparator 116responds to the difference between the signals picked up from thepotentiometers 106 and 112 and produces a negative error signal which isamplified in an amplifier 120 to energize a solenoid 121 of a reversecontactor 122.

FIG. 9 shows diagrammatically the armature 123 and field winding 124 ofthe electric motor 100 for the d.c. motor. A battery 125 is shown by wayof example as a suitable source of d.c. power for the motor 100. Onebrush 126 of the armature 123 is connected directly to a negative lead127 from the power source 125. 'A positive lead 128 is connectible by amain switch 129 to the positive pole of the power source 125. Thepositive brush 130 of the armature 123 is connected to an armature lead131. The forward contactor 119 has a contact arm 132 for connecting thepositive lead 128 to a first lead 133 to the field winding 124 and asecond contact arm 134 for connecting the armature lead 131 to a secondlead 135 from the field winding 124. Thus, when the contactor 119 isenergized the motor 100 is driven in aforward direction to raise thepickup conveyor 74. The reverse contactor 122 has a contact arm 136 forconnecting the positive lead 128 to the second field winding lead 135and a contact arm 137 for connecting the armature lead 131 to a resistor138 which leads to the first field winding lead 133. Thus, when thereverse contactor 122 is energized the motor 100 is driven in a reversedirection to lower the pickup conveyor 74 but at a comparatively slowspeed governed by the resistance of the resistor 138. Suitable interlockcontacts (not shown) may be provided on the contactors- 119 and 122 toprevent both contactors from being operated simultaneously in the eventof a fault.

In operation, as with the first embodiment, the pans containing bakedloaves of bread or the like product arrive from a cooler at therighthand end (FIGS. 6 and 7) of the pan conveyor 70 and proceed beneaththe feeler 102. The feeler 102 rides over the loaves and sets the sliderarm 105 of the potentiometer 106 at a position according to the heightof the loaves with respect to the height of the support 104. Acorresponding potential is thereby delivered to the comparators 115 and116. Generally, the pickup conveyor 74 will be initially too low so thatthe slider arm 105 of the potentiometer 116 delivers a higher potentialto the comparators 115 and 116. The positive comparator 115 thenresponds to the difference between these two potentials and delivers apositive error signal which is amplified by the amplifier 117 andenergizes the contactor 119. The motor 100 is thereby connected to thepower source 125 (the main switch 129 having previously been closed) andthe motor 100 rotates at full speed to raise the pickup conveyor 74.This causes the support 104 to be raised also whereby the slider arm 105of the potentiometer 106 is moved in a direction to reduce thedifference between the potentials from the slider arms 105 and 111 untilthis difference becomes too small for the comparator 115 to respond. Thecontactor 119 thereby releases to stop themotor 100 with the pickupconveyor 74 in a vertical position corresponding to the height of theloaves as measured by the feeler 102.

Should the size of the loaves be changed, then the feeler l02'willfallso that the potential on the slider arm 105 of the sensor potentiometer106 becomes less than the potential of the slider arm 111 of thepotentiometer 112. The comparator 1 16 now responds to the differencebetween the two potentials, which is now of an opposite sense, andproduces a negative error signal amplified by the amplifier 120 toenergize the reversing contactor 122. The motor 100 is now caused torotate in a reverse direction but rotates at a comparatively slow speeddue to the presence of the series resistor 138. The pickup conveyor 74and the support 104 for the feeler 102 are thereby gradually lowered tothe new height and stop when the difference between the potentials onthe two slider arms 105 and 111 becomes too small for the comparator 116 to respond.

It will be seen that in the absence of any pans being advanced on to thepan conveyor 70 the feeler 102 will adopt its lowermost positionillustrated and the pickup conveyor will gradually be lowered to itslowermost position. In practice, when changing over from one size loafto anotherthere will be a gap between the end of the pans of one sizeand the beginning of the pans of another size. During this gap thepickup conveyor 74 will be slowly lowered towards its lowermost positionand will then be rapidly raised again to the new height when the newsized loaves begin to arrive.

By arranging for the motor 100 to rotate at full speed for raising thepickup conveyor 74 it can be assured that this conveyor has reached therequired height before the pans advance beneath the pickup conveyor. Byarranging for the motor 100 to rotate comparatively slowly in thereverse direction it can be ensured that when there is, a gap betweenthe pans, resulting in release of the feeler 102, the last of the pansarrives beneath the pickup conveyor 74 before it has been lowered asignificant distance.

The operation of the pickup conveyor 74 to lift the loaves out of thepans'and deposit them on a discharge conveyor is as described withreference to the first embodiment. The position of the dischargeconveyor for the depanned products is shown by broken lines 140. One endof this discharge conveyor can be conveniently attached to the uprights91 and 92. Before the pans move beneath the pickup conveyor 74 they arealigned centrally on the pan conveyor 70 by the guide arms 84 in themanner previously described with reference to the first embodiment.

While the support 104 for the feeler 102 is shown as being verticallymovable on the frame .73 it can, if desired, be placed further away fromthe pickup conveyor 74, e.g. on the outlet end of the cooler, providedthat the speed'of rotation of the motor 100 is sufficiently slow in thereverse direction.

Naturally, other means and circuitry for operation of the-motor 100 arepossible. For example, the motor 100 might be a three phase motor whichis reversed by reversing the connections to two of the phase winding.The fast and slow speeds could be obtained by gear trains of differentratios selectively brought into operation by means of suitable clutches.

Again, the electronic circuit controlling the motor 100 may be modifiedby omitting the comparator 116 and the amplifier 120. In this case asingle contactor is used which, when energized, operates the motor 100in the forward direction and when de-energized operates the motor 100 inthe reverse direction. In this case the pickup conveyor 74 will becaused to oscillate in height about a mean position but withinsufficient amplitude to affect: operation of the pickup conveyor.

Whilst a potentiometer has been illustrated as. suitable means formeasuring; the height of the loaves relative to the height of the pickupconveyor 74 other means could be used, such as rows of photo-electriccells. Also, it would be possible to replace the screw jack 98 by ahydraulic jack of the kind described with reference to the firstembodiment. In this case the contactors 119 and 122 would be replaced bya suitable solenoid operated changeover valve and the resistor 138 wouldbe replaced by a throttle in one of the hydraulic lines.

Air blast nozzles (not shown) can be arranged above a grid 142 of rodsfor causing air to blast down between the loaves and the tins to loosenthe loaves. The grid 142 restrains the loaves from lifting right out ofthe pans.

What is claimed is:

1. A section depanner which is provided with means for automaticallyadjusting the height of the pickup conveyor responsively to the heightof the loaves to be removed from the pans including a movable feelerarranged in advanced the pickup conveyor for sensing the height of theproduct to be depanned, a hydraulic jack for. raising and lowering thepickup conveyor, and control means for operating said jack responsivelyto movement of said feeler.

2. A suction depanner as claimed in claim 1 in which said feeleroperates a hydraulic control valve for controlling operation of saidjack.

3. A section depanner which is provided with means for automaticallyadjusting the height of the pickup conveyor responsively to the heightof the loaves to be removed from the pans including a movable feelerarranged in advance of the pickup conveyor for sensing the height of theproduct to be depanned, a jack for raising and lowering the pickupconveyor comprising a screw jack and a reversible electric motor fordriving the screw jack, and control means for operating such jackresponsively to movement of said feeler.

4. A section depanner which is provided with means for automaticallyadjusting the height of the pickup conveyor responsively to the heightof the loaves to be removed from the pans including a movable feelerarranged in advance of the pickup conveyor for sensing the height of theproduct to be depanned, a jack for raising and lowering the pickupconveyor, and control means for operating said jack responsively tomovement of said feeler, said feeler being mounted on a forwardextension of a support frame for said pickup conveyor and is movablevertically therewith.

5. A suction depanner as claimed in claim 3 in which said feeleroperates an electrical transducer for controlling operation of saidjack.

6. A suction depanner as claimed in claim 5 in which said feeler ismounted on a fixed frame in advance of said pickup conveyor and in whicha feedback transducer is provided for indicating the actual height ofsaid pickup conveyor, said control means including means for comparingthe actual height of said pickup conveyor with the height of the productas measured by the feeler.

7. A suction depanner as claimed in claim 6 in which each of saidtransducers comprises an electric potentiometer with a slider movablerespectively by movement of the feeler and by vertical movement of thepickup conveyor.

8. A suction depanner as claimed in claim 7 in which said.potentiometers form two branches of a Wheatstone bridge circuit and inwhich said control means includes an electronic comparator connectedbetween the sliders of said potentiometers and an amplifier foramplifying an error signal produced by the comparator responsively tounbalance of the Wheatstone bridge circuit.

9. A suction depanner as claimed in claim 8 in which said jack comprisesa screw jack and a reversible electric motor for driving said screw jackand including reversing contactor means for the electric motor for thejack, said reversing contactor means being operable by the amplifiederror signal.

10. A suction depanner as claimed in claim 9 including circuit means forcausing said motor to rotate comparatively slowly when in reverse forlowering the pickup conveyor.

11. A suction depanner for removing bread, buns and the like foodproducts from pans including a pan conveyor, a vacuum pickup conveyorlocated above the pan conveyorfor removing the contents from pans movingalong the pan conveyor and means for automatically adjustingtheclearance between the pan conveying means and the vacuum pickupconveyor to a proper depanning distance as a function of the height ofthe product in the pans at a location on the pan conveyor upstreamrelative to the vacuum pickup conveyor.

12. A suction depanner as in claim 11 wherein said means comprises asensor operable in response to said height and drive means responsive tothe output of said sensor for effecting relative movement between thepan conveyor and the vacuum pickup conveyor.

13. A suction depanner as in claim 12 wherein said sensor is mountedupon said pan conveyor.

14. A suction depanner as in claim 12 wherein said sensor is mounted onsaid vacuum pickup conveyor.

1. A section depanner which is provided with means for automatically adjusting the height of the pickup conveyor responsively to the height of the loaves to be removed from the pans including a movable feeler arranged in advance of the pickup conveyor for sensing the height of the product to be depanned, a hydraulic jack for raising and lowering the pickup conveyor, and control means for operating said jack responsively to movement of said feeler.
 2. A suction depanner as claimed in claim 1 in which said feeler operates a hydraulic control valve for controlling operation of said jack.
 3. A section depanner which is provided with means for automatically adjusting the height of the pickup conveyor responsively to the height of the loaves to be removed from the pans including a movable feeler arranged in advance of the pickup conveyor for sensing the height of the product to be depanned, a jack for raising and lowering the pickup conveyor comprising a screw jack and a reversible electric motor for driving the screw jack, and control means for operating such jack responsively to movement of said feeler.
 4. A section depanner which is provided with means for automatically adjusting the height of the pickup conveyor responsively to the height of the loaves to be removed from the pans including a movable feeler arranged in advance of the pickup conveyor for sensing the height of the product to be depanned, a jack for raising and lowering the pickup conveyor, and control means for operating said jack responsively to movement of said feeler, said feeler being mounted on a forward extension of a support frame for said pickup conveyor and is movable vertically therewith.
 5. A suction depanner as claimed in claim 3 in which said feeler operates an electrical transducer for controlling operation of said jack.
 6. A suction depanner as claimed in claim 5 in which said feeler is mounted on a fixed frame in advance of said pickup conveyor and in which a feedback transducer is provided for indicating the actual height of said pickup conveyor, said control means including means for comparing the actual height of said pickup conveyor with the height of the product as measured by the feeler.
 7. A suction depanner as claimed in claim 6 in which each of said transducers comprises an electric potentiometer with a slider movable respectively by movement of the feeler and by vertical movement of the pickup conveyor.
 8. A suction depanner as claimed in claim 7 in which said potentiometers form two branches of a Wheatstone bridge circuit and in which said control means includes an electronic comparator connected between the sliders of said potentiometers and an amplifier for amplifying an error signal produced by the comparator responsively to unbalance of the Wheatstone bridge circuit.
 9. A suction depanner as claimed in claim 8 in which said jack comprises a screw jack and a reversible electric motor for driving said screw jack and including reversing contactor means for the electric motor for the jack, said reversing contactor means being operable by the amplified error signal.
 10. A suction depanner as claimed in claim 9 including circuit means for causing said motor to rotate comparatively slowly when in reverse for lowering the pickup conveyor.
 11. A suction depanner for removing bread, buns and the like food products from pans including a pan conveyor, a vacuum pickup conveyor located above the pan conveyor for removing the contents from pans moving along the pan conveyor and means for automatically adjusting the clearance between the pan conveying means and the vacuum pickup conveyor to a proper depanning distance as a function of the height of the product in the pans at a location on the pan conveyor upstream relative to the vacuum pickup conveyor.
 12. A suction depanner as in claim 11 wherein said means comprises a sensor operable in response to said height and drive means responsive to the output of said sensor for effecting relative movement between the pan conveyor and the vacuum pickup conveyor.
 13. A suction depanner as in claim 12 wherein said sensor is mounted upon said pan conveyor.
 14. A suction depanner as in claim 12 wherein said sensor is mounted on said vacuum pickup conveyor. 